River Road Generating Plant
Owned by Clark Public Utilities
Operated by GE Vernova248 MW, gas-fired 1 × 1 7FA.02-powered combined cycle equipped with a Foster Wheeler HRSG, and a GE A12 steam turbine, located in Vancouver, Wash
Plant manager: Robert Mash
Challenge. The HRSG high-pressure drum doors had a history of leaking. Some leaks caused forced outages; all leaks represented safety hazards for employees.
During annual outages, the drum doors were a challenge to close and seat properly for several reasons, including these:
- Bent and worn drum-door hinge hardware, which often caused misalignment of the door-to-drum connection.
- Pitted drum and door seating surfaces allowed a pathway for steam to leak.
- Worn drum-door bolts and strongbacks resulted in over-tightening (over torque).
- The heavy weight of the doors required personnel to use pry bars and wood blocks to center the drum doors in the drum opening (the existing drum-door leveling blocks did not perform well).
Solution. River Road is a baseload facility with very little downtime. Thus, all remedies listed below were implemented at the same time:
- Performed “phonograph-groove” machining on drum manway and door gasket sealing surfaces (Fig 1).
- Replaced the drum-door internal hinge assemblies.
- Replaced drum-door strongbacks (Fig 2).
- Replaced drum-door bolting with Superbolt™ and nut design.
- Replaced existing drum-door leveling blocks with an improved style (Fig 3).
- Completed machining and installing all parts during a single annual outage.
Results.
- Performed several startups and shutdowns post-outage with zero leaks to date.
- Project provided the opportunity for team participation and collaboration to identify all related issues and research potential solutions.
- The new drum-door leveling system works perfectly.
- The Superbolt and nut system ensures proper torque is applied to drum doors and can be accomplished with a small ratchet torque wrench.
- Enhanced safety was achieved for all personnel working near or passing through the vicinity of the drum doors.
- The physical effort and time required for opening and closing drum doors was reduced significantly.
Project participants:
Ken Roach, maintenance manager
Mike Buhman, mechanic
River Road’s 2023 Best Practices